Born Isle of Guernsey, United Kingdom, 15 January 1815
Died London, England, 19 April 1889
Warren de la Rue pioneered the application of photography to the study of the Moon and Sun, in the process demonstrating the value of an equatorially mounted, clock-driven reflecting telescope as a camera, techniques that greatly accelerated the evolution of the new science of astrophysics. The son of Thomas de la Rue, a printer, and Jane (néeWarren), de la Rue was educated at the Collège Sainte-Barbe in Paris and later studied with the noted chemist August Wilhelm Hofmann in London. While still in his youth, de la Rue joined his father’s printing business, where he showed a talent for mechanical innovation. He was among the first printers to adopt the electrotyping process and was coinventor (with Edwin Hill) of the envelope-making machine.
De la Rue’s earliest scientific contributions were in the field of chemistry. In 1836, he published his first paper, describing an improvement to the Daniell cell, a form of copper-zinc battery. He helped edit an English version of the first two volumes of the Jahresbericht der Chemieby Justus von Liebig and Heinrich Kopp. Much later, between 1868 and 1883, he conducted experiments on electrical discharges in gases, accumulating a wealth of data but resulting in no theoretical “advances.”
James Nasmyth , inventor of the steam-driven pile driver and a friend of de la Rue, introduced him to astronomy in the late 1840s. Nasmyth was a noted lunar observer whose detailed drawings of the Moon’s surface brought him wide acclaim. Impressed by Nasmyth’s achievement, de la Rue built a small observatory at Canonbury, England (later moved to Cranford in Middlesex), where he installed a Newtonian-style reflecting telescope of his own design, incorporating a 13-in-diameter speculum-metal mirror. Nasmyth provided the cast speculum-metal disks from which de la Rue ground and polished excellent mirrors for his telescope. The perfection of de la Rue’s mirrors was due in no small part to the mirror-making machine he built after examining similar machines built by Nasmyth and especially a machine designed and constructed by William Lassell . De la Rue’s machine more completely controlled the relative motions of the mirror and the tool against which it was being ground and polished, ensuring that all diameters were equally and uniformly traversed in the course of the grinding and polishing operations.
Like Nasmyth, de la Rue’s first foray into astronomy involved the hand rendering of the Sun, Moon, and planets. In 1850, he published a highly praised drawing of Saturn. De la Rue turned his attention to celestial photography in late 1852 after viewing the lunar daguerreotypes of Harvard astronomer William Bond and photographer John Adams Whipple at the 1851 Crystal Palace exhibition in London. De la Rue adopted the new wet-collodion photographic process with good result. After extensive experimentation and the installation, in 1857, of a clock drive to his telescope, he obtained a series of exquisitely detailed lunar images. The images, although small, were so clear that they could be enlarged to almost 8 in. In particular, de la Rue was lauded for his extraordinary stereoscopic photographs of the Moon, which revealed surface features never before seen. A bound set of reproductions of de la Rue’s lunar photographs was published in 1860. De la Rue’s photographs played a major role in British efforts to settle questions about the possible volcanic origin of lunar features, and detection of continuing volcanic activity on the Moon. He participated in a panel of scientists charged with considering this specific question. The panel included, among its 11 members William Parsons , Third Earl of Ross, and Sir John Herschel .
Following a recommendation by John Herschel in 1847 (repeated more forcefully in 1854), de la Rue developed a photoheliograph, a specialized telescope with which he maintained a daily photographic record of sunspot activity. The instrument, a refractor of 3-in aperture, projected a magnified image of the Sun through a grid that was recorded as part of the solar image on a wet-collodion plate. The necessarily short exposure time was controlled with a shutter. The photoheliograph, installed at Kew in 1858, produced images of the solar disk that revealed details that could not be observed visually. The daily solar photographic survey was continued at Kew until 1872, at which time it was transferred to Greenwich as the first step taken by the Royal Observatory in the emerging field of astrophysics.
The photoheliograph was temporarily removed from Kew by de la Rue to photograph the total solar eclipse of 18 July 1860, from Rivabellosa, Spain. De la Rue’s photographs, along with others obtained about 250 miles farther east on the path of the total eclipse by Angelo Secchi and others, demonstrated conclusively that the luminous, “flame-like” outbursts (now known as prominences) seen during eclipse were of solar, not lunar, origin.
In 1861, de la Rue demonstrated through stereoscopic imagery that sunspots were depressions in the Sun’s atmosphere. He also achieved a modest measure of success with stellar photography in the 1860s. Through his own detailed reports of his procedures to various scientific organizations, de la Rue paved the way for subsequent photographic progress by his astronomical colleagues.
De la Rue was president of the British Chemical Society from 1867 to 1869 and in 1879/1880. He was elected a fellow of the Royal Society in 1850 and later a corresponding member of the French Academy of Sciences. He served as president of the Royal Astronomical Society from 1864 to 1866. For his contributions to the practice of celestial photography, de la Rue received the Royal Astronomical Society’s Gold Medal in 1862, the Royal Society’s Royal Medal in 1864, and the Lalande Prize in 1865. In 1840, de la Rue married Georgiana Bowles; they had four sons and a daughter.